Because the effort achieve both isn't worth it. If anything, I'd rather have different groups attempting different goals.
In the Civil Rights Movement, it wasn't just MLK jr. Sure he was there with his disruptive protests, and no, he wasn't gaining people's approval for that but making it known what will be done if people don't listen.
But there were others. There was Malcolm, there was Stokley, Septima Poinsette Clark, Diane Nash, Ella Baker. Some mostly spoke and weren't as disruptive, some were student protesters that were VERY disruptive.
And then there were the Panthers and the Deacons. The folks that made it known that they will protect their own by any means necessary, approval be damned.
Frankly, black folks in the US need all those different styles and we are surely lacking on the third. They need the status quo to be willing to listen, but also afraid of what happens when they don't.